Year	Percent
1998-01-01	38.6720585956239
1999-01-01	38.6253384584958
2000-01-01	39.0420675904624
2001-01-01	38.8613285670907
2002-01-01	39.3001983835965
2003-01-01	39.9835542855944
2004-01-01	40.1768893406398
2005-01-01	40.5312026880124
2006-01-01	41.1626617074990
2007-01-01	41.3601506062632
2008-01-01	41.6883681205207
2009-01-01	41.1882222776794
2010-01-01	39.8019755959318
2011-01-01	36.8632943709625
2012-01-01	33.6903965292046
2013-01-01	32.1688075222668